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Abstract:

The present invention provides a succinimide compound represented by the
following formula (1-1) or (1-2), and a lubricating oil additive and a
lubricating oil composition which contain the succinimide compound.
##STR00001## wherein R represents an alkyl group or an alkenyl group
having a number-average molecular weight of 500 or greater and less than
5000.
##STR00002## wherein R represents an alkyl group or an alkenyl group
having a number-average molecular weight of 500 or greater and less than
5000.

Claims:

1. A succinimide compound represented by the following formula (1-1) or
(1-2): ##STR00009## wherein R represents an alkyl group or an alkenyl
group having a number-average molecular weight of 500 or greater and less
than 5000; ##STR00010## wherein R represents an alkyl group or an
alkenyl group having a number-average molecular weight of 500 or greater
and less than 5000.

2. The succinimide compound according to claim 1, wherein R in the
formula (1-1) or (1-2) is a group derived from polyisobutene having a
number-average molecular weight of 500 or greater and less than 5000.

3. A lubricating oil additive comprising the succinimide compound
according to claim 1.

4. A lubricating oil composition comprising a lubricating base oil and
the succinimide compound according to claim 1.

5. The lubricating oil composition according to claim 4, further
comprising a phosphorus compound.

Description:

TECHNICAL FIELD

[0001] The present invention relates to a novel succinimide compound, and
a lubricating oil additive and a lubricating oil composition which
contain the compound,

BACKGROUND ART

[0002] A succinimide compound is used as an ashless dispersant dispersing
an insoluble to be generated, in oil in the field of a lubricating oil
for an internal combustion engine such as a gasoline engine oil or a
diesel engine oil. On the other hand, the succinimide compound is used as
a friction modifier enhancing a friction force in the field of a driving
system lubricating oil for an automatic transmission or the like.

[0003] A succinimide compound obtained by the reaction between
high-molecular succinic anhydride substituted with an alkenyl or alkyl
group, and polyalkylene polyamine, or the like has been known as a
conventional succinimide compound (see the following Patent

[0008] It is an object of the present invention to provide a novel
succinimide compound useful for uses such as an ashless dispersant in a
lubricating oil for an internal combustion engine, and a friction
modifier in a driving system lubricating oil, and a lubricating oil
additive and a lubricating oil composition which contain the compound.

Solution to Problem

[0009] Then, the present invention provides a succinimide compound
represented by the following formula (1-1) or (1-2).

##STR00003##

[0010] [In the formula (1-1), R represents an alkyl group or an alkenyl
group having a number-average molecular weight of 500 or greater and less
than 5000.]

##STR00004##

[0011] [In the formula (1-2), R represents an alkyl group or an alkenyl
group having a number-average molecular weight of 500 or greater and less
than 5000.]

[0012] Since the succinimide compound of the present invention has a very
excellent characteristic as compared with a conventional succinimide
compound, the succinimide compound is useful for uses such as an ashless
dispersant in a lubricating oil for an internal combustion engine, and a
friction modifier in a lubricating oil for a driving device.

[0013] For example, recently, a friction coefficient higher than that in
the conventional manner is required for a driving system lubricating oil
in order to efficiently convert a friction force in an automatic
transmission into a driving force in view of improving fuel efficiency.
However, when the conventional succinimide compounds described in the
above Patent Literatures 1 to 3 are used, a sufficient friction
characteristic-improving effect can not be obtained. This is considered
to be because the friction characteristic-improving effect of the
succinimide compound itself is insufficient in the case of the
conventional succinimide compound, and the increased amount of
succinimide changes adsorbability to a metal surface, to lose the balance
of the other additive agent, thereby reducing friction characteristics.

[0014] On the other hand, since the succinimide compound of the present
invention has an excellent friction characteristic-improving effect as
compared with the conventional succinimide compound, the high friction
coefficient for efficiently converting the friction force in the
automatic transmission into the driving force can be achieved, to improve
the fuel efficiency.

[0015] In the succinimide compound of the present invention, R in the
formula (1-1) or (1-2) is preferably a group derived from polyisobutene
having a number-average molecular weight of 500 or greater and less than
5000.

[0017] The present invention provides a lubricating oil composition
containing a lubricating base oil and the above succinimide compound of
the present invention.

[0018] Preferably, the lubricating oil composition of the present
invention further contains a phosphorus compound.

Advantageous Effects of Invention

[0019] The present invention can provide a novel succinimide compound
useful for uses such as an ashless dispersant in a lubricating oil for an
internal combustion engine, and a friction modifier in a driving system
lubricating oil, and a lubricating oil additive and a lubricating oil
composition which contain the compound,

Description of Embodiments

[0020] Hereinafter, a preferred embodiment of the present invention will
be described in detail,

[0021] [Succinimide Compound]

[0022] A succinimide compound according to the embodiment has a structure
represented by the following formula (1-1) or (1-2):

##STR00005##

[0023] [In the formula (1-1), R. represents an alkyl group or an alkenyl
group having a number-average molecular weight of 500 or greater and less
than 5000.]

##STR00006##

[0024] [In the formula (1-2), R represents an alkyl group or an alkenyl
group having a number-average molecular weight of 500 or greater and less
than 5000.]

[0025] A polybutenyl group and a polyisobutenyl group are preferable as
the alkyl group or the alkenyl group represented by R in the formula
(1-1) or (1-2), The number-average molecular weight of the alkyl group or
the alkenyl group represented by R is 500 or greater and 5000 or less,
preferably 700 to 4000, and more preferably 800 to 3,500.

[0026] The succinimide compound represented by the formula (1-1) can be
obtained by reacting maleinized alkyl or maleinized alkenyl having the
alkyl group or the alkenyl group having a number-average molecular weight
of 500 or greater and less than 5000 with phenylalanine
(2-amino-3-phenylpropionic acid). The above maleinized alkyl or
maleinized alkenyl to be used as a raw material can be obtained by
reacting polyalkene (polybutene and polyisobutene or the like) having a
number-average molecular weight of 500 or greater and less than 5000 with
maleic anhydride, for example.

[0027] When the maleinized alkyl or the maleinized alkenyl is reacted with
the phenylalanine, the charge ratio of the maleinized alkyl or the
maleinized alkenyl/the phenylalanine can be preferably set to 1/1 to 1/2
at a molar ratio, more preferably 1/1 to 1/1.8, still more preferably
1/1.1 to 1/1.6, and particularly preferably 1/1.2 to 1/1.5. The target
succinimide compound can be more certainly obtained by the reaction of
the above ratio of the range.

[0028] In the above reaction, a succinimide compound represented by the
following formula (2-1) may be generated as a by-product in addition to
the succinimide compound represented by the formula (1-1). In this case,
the succinimide compound represented by the formula (2-1) is separated
and removed from the reaction product, and only the succinimide compound
represented by the formula (1-1) may be a lubricating oil additive.
Alternatively, a mixture of the succinimide compound represented by the
formula (1-1) and the succinimide compound represented by the formula
(2-1) may be used as the lubricating oil additive.

##STR00007##

[0029] In the formula (2-1), R represents an alkyl group or an alkenyl
group having a number-average molecular weight of 500 or greater and less
than 5000. n represents an integer of 1 or greater. Although n is usually
1 or 2, n tends to be increased when the ratio of the phenylalanine to
the maleinized alkyl or the maleinized alkenyl in a raw material during
synthesis is increased.

[0030] The succinimide compound represented by the formula (1-2) can be
obtained by reacting maleinized alkyl or maleinized alkenyl having an
alkyl group or an alkenyl group having a number-average molecular weight
of 500 or greater and less than 5000 with phenylalanine
(2-amino-3-phenylpropionic acid). The above maleinized alkyl or
maleinized alkenyl to be used as a raw material can be obtained by
reacting polyalkene (polybutene and polyisobutene or the like) having a
number-average molecular weight of 500 or greater and less than 5000 with
maleic anhydride, for example.

[0031] When the maleinized alkyl or the maleinized alkenyl is reacted with
the phenylalanine, the charge ratio of the maleinized alkyl or the
maleinized alkenyl/the phenylalanine can be preferably set to 1/1 to 1/2
at a molar ratio, more preferably 1/1 to 1/1.8, still more preferably
1/1.1 to 1/1.6, and particularly preferably 1/1.2 to 1/1.5. The target
succinimide compound can be more certainly obtained by the reaction of
the above ratio of the range.

[0032] In the above reaction, a succinimide compound represented by the
following formula (2-2) may be generated as a by-product in addition to
the succinimide compound represented by the formula (1-2). In this case,
the succinimide compound represented by the formula (2-2) is separated
and removed from the reaction product, and only the succinimide compound
represented by the formula (1-2) may be a lubricating oil additive.
Alternatively, a mixture of the succinimide compound represented by the
formula (1-2) and the succinimide compound represented by the formula
(2-2) may be used as the lubricating oil additive,

##STR00008##

[0033] In the formula (2-2), R represents an alkyl group or an alkenyl
group having a number-average molecular weight of 500 or greater and less
than 5000, n represents an integer of 1 or greater. Although n is usually
1 or 2, n tends to be increased when the ratio of the phenylalanine to
the maleinized alkyl or the maleinized alkenyl in a raw material during
synthesis is increased,

[0034] The succinimide compound represented by the formula (1-1) or (1-2)
may be used as it is without being borated (that is, as a non-borated
suceinimide compound), or may be used as a borated succinimide compound.
Furthermore, the borated succinimide compound and the non-borated
succinimide compound may be used in combination.

[0035] The borated succinimide compound can be obtained by reacting the
succinimide compound represented by the formula (1-1) or (1-2) with a
boron-containing compound at a temperature of usually 50 to 250°
C., and preferably 100 to 200° C. Examples of the boron-containing
compound include boron oxide, halogenized boron, boric acid, boric
anhydride, and a boric acid ester. Any one of these boron-containing
compounds may be used alone, or two or more thereof may be used in
combination.

[0036] [Lubricating Oil Additive]

[0037] A lubricating oil additive according to the embodiment contains the
succinimide compound represented by the above formula (1-1) or (1-2). The
lubricating oil additive may contain only the succinimide compound
represented by the formula (1-1) or (1-2), and may be a mixture of the
succinimide compound represented by the formula (1-1) or (1-2) and other
additive agent. The lubricating oil additive may further contain a
diluent for dissolving the additive agent.

[0038] Since the succinimide compound represented by the formula (1-1) or
(1-2) has excellent compatibility with various additive agents used in
the field of the lubricating oil, the other additive agent used in
combination is not particularly limited when the lubricating oil additive
according to the embodiment is the mixture of the succinimide compound
represented by the formula (1-1) or (1-2) and the other additive agent.
Therefore, the kind of the other additive agent used in combination with
the succinimide compound represented by the formula (1-1) or (1-2), and
the mixing ratio thereof can be suitably selected according to the use
and the object of the lubricating oil additive, Specific examples of the
other additive agent used in combination will be described later.

[0039] A lubricating oil composition according to the embodiment contains
a lubricating base oil and the succinimide compound represented by the
above formula (1-1) or (1-2). A mode containing the lubricating base oil
and the lubricating oil additive according to the above embodiment is
included in the lubricating oil composition,

[0040] The lubricating base oil is not particularly limited, and both a
mineral oil and a synthetic oil can be used. Various mineral oils which
have conventionally been known can be used as the mineral oil, and
examples thereof include a paraffin-based mineral oil, an
intermediate-based mineral oil, and a naphthene-based mineral oil,
Specific examples include a light neutral oil, an intermediate neutral
oil, a heavy neutral oil, and a bright stock by solvent refining or
hydrogen refining. A GTL base oil in which wax is isomerized or the like
may be used, and the higher the refining degree is, the higher the effect
thereof is.

[0041] Similarly, various synthetic oils which have conventionally been
known can be used as the synthetic oil. For example, poly-α-olefin
(including an α-olefm copolymer), polybutene, a polyol ester, a
dibasic ester, a phosphoric ester, a polyphenyl ether, alkylbenzene,
alkylnaphthalene, polyoxyalkylene glycol, neopentyl glycol, a silicone
oil, trimethylolpropane, pentaerythritol, and a hindered ester or the
like can be used.

[0042] Any one of these lubricating base oils can be used alone, or two or
more thereof can be used in combination, and the mineral oil and the
synthetic oil may be used in combination.

[0043] The kinetic viscosity of the lubricating base oil can be suitably
selected according to the use and the object of the lubricating oil
composition. When the lubricating oil composition according to the
embodiment is used as a driving system lubricating oil, for example, the
kinetic viscosity of the lubricating base oil at 100° C. is
preferably 1 to 30 mm2/s, more preferably 2 to 20 mm2/s, and
still more preferably 3 to 10 mm2/s, When the kinetic viscosity at
100° C. is in the above range, the friction of a sliding part such
as a gear bearing or a clutch of an automatic transmission can
sufficiently be reduced, and the low-temperature characteristic thereof
is also good. On the other hand, when the kinetic viscosity at
100° C. is greater than 30 mm2/s, fuel consumption tends to
be reduced, and low-temperature viscosity tends to be excessively
increased. The kinetic viscosity of less than 1 mm2/s at 100°
C. may cause the reduction of lubricating performance such as the
increase of the wear amount of the sliding part such as the gear bearing
or the clutch of the automatic transmission, or cause high evaporativity
to increase the amount of consumption of a lubricating oil.

[0044] The % CA of the lubricating base oil is preferably equal to or
less than 20 in view of the low-temperature characteristic, and
particularly more preferably equal to or less than 10.

[0045] The content of the succinimide compound represented by the formula
(1-1) or (1-2) in the lubricating oil composition according to the
embodiment is preferably 0.01 to 30% by mass, more preferably 0.05 to 20%
by mass, and still more preferably 0.1 to 10% by mass in view of
effectively exhibiting the addition effect thereof. When two or more of
the succinimide compounds are used, the total of the contents thereof is
preferably in the above range.

[0046] The lubricating oil composition according to the embodiment can
further contain various additive agents represented by an ashless
dispersant and/or a friction modifier, a metal-based cleaning agent, a
viscosity index improver, an extreme-pressure agent, an antioxidant, a
corrosion inhibitor, an antifoaming agent, and a colorant or the like
except the succinimide compound represented by the formula (1-1) or
(1-2), if needed in order to further improve the performance thereof. Any
one of these additive agents can be used alone, or two or more thereof
can be used in combination.

[0047] Examples of the friction modifier except the succinimide compound
represented by the formula (1-1) or (1-2) include a fatty acid ester, a
fatty acid amide, or a phosphorus compound such as a phosphoric ester, a
phosphite, and a thiophosphoric acid ester, an organic molybdenum
compound such as MoDTP or MoDTC, an organic zinc compound such as ZnDTP,
an organic boron compound such as alkyl mercaptylborate, and a solid
lubricant-based friction modifier such as graphite, molybdenum disulfide,
an antimony sulfide, a boron compound, or polytetrafluoroethylene; of
these, the phosphorus compound is preferable. The content of the friction
modifier is usually 0.1 to 10% by mass based on the total amount of the
lubricating oil composition,

[0048] Examples of the antioxidant include an amine-based antioxidant such
as alkylated diphenylamine, phenyl-α-naphthylamine, or
alkylated-α-naphthylamine, and a phenol-based antioxidant such as
2,6-di-t-butyl-4-methyl phenol or 4,4'-methylene
bis(2,6-di-t-butylphenol). The content of the antioxidant is usually 0.05
to 5% by mass based on the total amount of the lubricating oil
composition.

[0049] Examples of the metal-based cleaning agent include calcium
sulfonate, magnesium sulfonate, barium sulfonate, calcium salicylate,
magnesium salicylate, calcium phenate, and barium phenate; the content of
the metal-based cleaning agent is usually 0.1 to 10% by mass based on the
total amount of the lubricating oil composition.

[0050] Examples of the viscosity index improver include a
polymethacrylate-based, polyisobutene-based, ethylene-propylene
copolymer-based, and styrene-butadiene hydrogenated copolymer-based
viscosity index improvers. The content of the viscosity index improver is
usually 0.5 to 35% by mass based on the total amount of the lubricating
oil composition.

[0051] The use of the lubricating oil composition according to the
embodiment is not particularly limited, and the lubricating oil
composition can be used in wide fields such as a lubricating oil for an
internal combustion engine and a driving system lubricating oil. Since
the lubricating oil composition according to the embodiment contains the
succinimide compound represented by the formula (1-1) or (1-2), for
example, the lubricating oil composition can achieve a high static
friction coefficient as compared with a conventional succinimide compound
(a high torque volume of a wet friction material), and is suitable as an
automatic transmission oil and a continuously variable transmission oil.
The lubricating oil composition can be used as a lubricating oil for a
construction machine and a farm machine which are provided with a
transmission having a wet clutch and a wet brake, a manual transmission,
a two-wheeled vehicle gasoline engine, a diesel engine, a gas engine, and
a shock absorber oil or the like.

EXAMPLES

[0052] Hereinafter, the present invention will be more specifically
described based on Examples and Comparative Examples, and the invention
is not limited to these Examples.

Example 1

Synthesis of Succinimide Compound I

[0053] After 1.0 mol of polyisobutene (number-average molecular weight:
1000) and 1.0 mol of maleic anhydride were placed in an autoclave of 2000
mL, the temperature thereof was raised to 220° C. for 1.5 hours,
and the reaction was performed for 4 hours after the temperature reached
220° C. After the completion of the reaction, n-hexane was added
to the obtained product, and these were stirred, and the liquid was
filtered to remove an insoluble. After n-hexane was removed from the
filtrate by atmospheric distillation, the maleic anhydride was removed at
220° C. under reduced pressure to obtain maleinized polyisobutene.

[0054] On the other hand, 0.008 mol of phenylalanine was crushed in a
mortar, and the phenylalanine was placed in a four-necked flask of 100
mL, to which xylene was added. Next, the reaction was performed at
165° C. for 24 hours while 0.004 mol of the maleinized
polyisobutene dissolved in the xylene and obtained was dropped. After the
completion of the reaction, residual amino acid was removed by
filtration, and a solvent was removed by distillation under reduced
pressure, to obtain a succinimide compound L The infrared absorption
spectrum and elemental analysis of the obtained succinimide compound I
were conducted to confirm the structure represented by the formula (1-2).
The content nitrogen was 1.15 (theoretical value: 1.22) %.

Example 2

Synthesis of Succinimide Compound II

[0055] After 1.0 mol of polyisobutene (number-average molecular weight:
2300) and 1.0 mol of maleic anhydride were placed in an autoclave of 2000
mL, the temperature thereof was raised to 220° C. for 1.5 hours,
and the reaction was performed for 4 hours after the temperature reached
220° C. After the completion of the reaction, n-hexane was added
to the obtained product, and these were stirred, and the liquid was
filtered to remove an insoluble. After n-hexane was removed from the
filtrate by atmospheric distillation, the maleic anhydride was removed at
220° C. under reduced pressure to obtain maleinized polyisobutene.

[0056] On the other hand, 0.008 mol of phenylalanine was crushed in a
mortar, and the phenylalanine was placed in a four-necked flask of 100
mL, to which xylene was added. Next, the reaction was performed at
165° C. for 24 hours while 0.004 mol of the maleinized
polyisobutene dissolved in the xylene and obtained was dropped. After the
completion of the reaction, residual amino acid was removed by
filtration, and a solvent was removed by distillation under reduced
pressure, to obtain a succinimide compound IL The infrared absorption
spectrum and elemental analysis of the obtained succinimide compound II
were conducted to confirm the structure represented by the formula (1-2).
The content nitrogen was 0.54 (theoretical value:

Example 3

Synthesis of Succinimide Compound III

[0057] After 1.0 mol of polyisobutene (number-average molecular weight:
1000) and 1.0 mol of maleic anhydride were placed in an autoclave of 2000
mL, the temperature thereof was raised to 220° C. for 1.5 hours,
and the reaction was performed for 4 hours after the temperature reached
220° C. After the completion of the reaction, n-hexane was added
to the obtained product, and these were stirred, and the liquid was
filtered to remove an insoluble. After n-hexane was removed from the
filtrate by atmospheric distillation, the maleic anhydride was removed at
220° C. under reduced pressure to obtain maleinized polyisobutene.

[0058] On the other hand, 0.008 mol of phenylalanine was crushed in a
mortar, and the phenylalanine was placed in a four-necked flask of 100
mL, to which xylene was added, Next, the reaction was performed at
165° C. for 24 hours while 0,004 mol of the maleinized
polyisobutene dissolved in the xylene and obtained was dropped. After the
completion of the reaction, residual amino acid was removed by
filtration, and a solvent was removed by distillation under reduced
pressure, to obtain a succinimide compound I. The infrared absorption
spectrum and elemental analysis of the obtained succinimide compound I
were conducted to confirm the structure represented by the formula (1-1).
The content nitrogen was 1.15 (theoretical value: 1.22) %.

Example 4

Synthesis of Succinimide Compound IV

[0059] After 1,0 mol of polyisobutene (number-average molecular weight:
2300) and 1.0 mol of maleic anhydride were placed in an autoclave of 2000
mL, the temperature of the autoclave was raised to 220° C. for 1,5
hours, and the reaction was performed for 4 hours after the temperature
reached 220° C. After the completion of the reaction, n-hexane was
added to the obtained product, and these were stirred, and the liquid was
filtered to remove an insoluble. After n-hexane was removed from the
filtrate by atmospheric distillation, the maleic anhydride was removed at
220° C. under reduced pressure to obtain maleinized polyisobutene,

[0060] On the other hand, 0.008 mol of phenylalanine was crushed in a
mortar, and the phenylalanine was placed in a four-necked flask of 100
mL, to which xylene was added. Next, the reaction was performed at
165° C. for 24 hours while 0.004 mol of the maleinized
polyisobutene dissolved in the xylene and obtained was dropped. After the
completion of the reaction, residual amino acid was removed by
filtration, and a solvent was removed by distillation under reduced
pressure, to obtain a succinimide compound II. The infrared absorption
spectrum and elemental analysis of the obtained succinimide compound II
were conducted to confirm the structure represented by the formula (1-1).
The content nitrogen was 0.54 (theoretical value: 0.57) %.

Comparative Example 1

Synthesis of Succinimide Compound V

[0061] After 1.0 mol of polyisobutene (number-average molecular weight:
1000) and 1.0 mol of maleic anhydride were placed in an autoclave of 2000
mL, the temperature thereof was raised to 220° C. for 1.5 hours,
and the reaction was performed for 4 hours after the temperature reached
220° C. After the completion of the reaction, n-hexane was added
to the obtained product, and these were stirred, and the liquid was
filtered to remove sludge. After n-hexane was removed from the filtrate
by atmospheric distillation, the maleic anhydride was removed at
220° C. under reduced pressure to obtain maleinized polyisobutene.

[0062] 1.7 mol of diethylene triamine and xylene were placed in a
separable flask of 2 L. Next, the reaction was performed at 145 to
155° C. for 11 hours while 0.17 mol of the maleinized polybutene
dissolved in the xylene and obtained was dropped. After the completion of
the reaction, a solvent was removed by atmospheric distillation, and
residual diethylene triamine was removed by distillation under reduced
pressure, to obtain a succinimide compound V.

Examples 5 to 16 and Comparative Examples 2 to 4

Preparation and Evaluation Test of Lubricating Oil Composition

[0063] In Examples 5 to 16 and Comparative Examples 2 to 4, lubricating
oil compositions were prepared using a mineral oil of an SAE10 distillate
(kinetic viscosity at 100° C.: 4.1 mm2/s) as a lubricating
base oil, a succinimide compound 1, II, III, IV or V, and additive agents
shown in Tables 1 and 2. The compositions of the lubricating oil
compositions are shown in Tables 1 to 3.

[0064] Next, intermetallic friction coefficients of the lubricating oil
compositions of Examples 5 to 16 and Comparative Examples 2 to 4 were
evaluated using an LFW-1 test machine. The test conditions: surface
pressure, slide rate, test temperature, and test time were set to 0.8
GPa, 0.2 m/s, 80° C., and 1 hour, respectively, and the
intermetallic friction coefficients were evaluated using an average
friction coefficient obtained by averaging the friction coefficients
within the time. The obtained results are shown in Tables 1 to 3.

[0065] The succinimide compound, the lubricating oil additive, and the
lubricating oil composition of the present invention can be used in the
wide field of the lubricating oils, and are particularly suitable as an
automatic transmission oil and a continuously variable transmission oil
which require a high static friction coefficient.